Initial commit

Nothing has actually been tested yet.

src/menu.h

@@ -0,0 +1,31 @@
+#ifndef NMI_MENU_H
+#define NMI_MENU_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stddef.h>
+
+typedef enum {
+    NMI_MENU_LOCATION_MAIN_MENU = 1,
+    NMI_MENU_LOCATION_READER_MENU = 2,
+} nmi_menu_location_t;
+
+typedef struct {
+    nmi_menu_location_t loc;
+    const char *lbl;
+    const char *arg;
+    int (*execute)(const char *arg, char **out_err); // can block, must return 0 on success, nonzero with out_err set to the malloc'd error message on error
+} nmi_menu_entry_t;
+
+// nmi_menu_hook hooks a dlopen'd libnickel handle to add the specified menus,
+// and returns 0 on success, or 1 with err_out (if provided) set to the malloc'd
+// error message on error. The provided configuration and all pointers it
+// references must remain valid for the lifetime of the program (i.e. not stack
+// allocated).
+int nmi_menu_hook(void *libnickel, nmi_menu_entry_t *entries, size_t entries_n, char **err_out);
+
+#ifdef __cplusplus
+}
+#endif
+#endif